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Is there a bolt on application or is the stock one the only fit. Want to machine holes around disk.
 

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i dunno if anything else is an exact fit, but from my short experiece with my cx....anything has to be better than the factory front brake.
 

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there are lots of other honda models that use the same diamter, drop, and hole pattern as the stock bike so you can drill, slot etc quite easily. However a 2nd disc and caliper or larger discs and calipers and mounts will yield better results. The stock master cylinder feels wooden as its really intended for a twin disc setup
 

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According to the brake experts it's not advised to drill discs, the ones you buy had the holes originally cast in them then finished by machining. Something to do with tempering of the metal and/or possibly introducing areas subject to stress cracks.



The whole idea of drilled/slotted is to allow the heated gasses between the disk and pad to escape, a pad with a single slot will work better than a solid one if you have a choice.
 

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According to the brake experts it's not advised to drill discs, the ones you buy had the holes originally cast in them then finished by machining. Something to do with tempering of the metal and/or possibly introducing areas subject to stress cracks.



The whole idea of drilled/slotted is to allow the heated gasses between the disk and pad to escape, a pad with a single slot will work better than a solid one if you have a choice.
I feel that drilling of rotors is a okay idea. Do not champfer the holes de-burr only. The one of the reasons holes are effective is the pads get better inital bite with holes. Another reason they are effecitve is "out gassing" The gases given off by the friction get trapped between the rotor and the brake pads. The holes or grooves allow the gasses a place to go and yield better contact of pad to disc (this was mentioned in another post). Lighter weight, the rotor(s) not only spin causing a flywheel effect but are also unsprung weight. When drilling make sure you have an overlaping pattern so as not to leave wear ridges. It's also possible to overdrill a rotor, removing too much mass leaves little left to sink the heat which is how brakes work. It's no mystery that virtually all modern rotors are drilled. When drilling use a lot of cooling fluid to not over heat the drill bit or the rotors. I would use a center drill first, then a small bit then my final size. I'm sure there are at few machinists out there that can add to or correct any comments such as proper feed rate/speed.

Cheers, 50gary
 

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Due to the possibility of stress cracks causing the disc to fracture I personally wouldn't do it. I'm not saying people haven't done it, but I wouldn't for safety reasons if nothing else.



Surely there's a choice of rotors already drilled or slotted that can be found to fit our bikes? Slotted is better anyway.
 

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well i am no expert by any means but why is slotted better than drilled? i under stand anything is better than no slots or drill but i have been tossing the idea of dual brakes around for a while now and if i was going to do it i was going to drill the rotors out.....
 

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well i am no expert by any means but why is slotted better than drilled? i under stand anything is better than no slots or drill but i have been tossing the idea of dual brakes around for a while now and if i was going to do it i was going to drill the rotors out.....


Think about it, the main reason for drilling &/or slotting is to allow the superheated gasses to escape from between the pads and disc surface itself. Slots are free-flowing to the outside air, they also cool down better. They also maintain the full integrity of the disc shape which contributes to strenght and exposes the maximum amount of metal surface to the cooling air.



While it's true either method reduces the weight a little, they say that percentagewise it isn't much or you've pushed the margin of safety.



In addition, it's just the experience of professional race car designers however recently many have gone back to solid rotors and changed the pad design to deal with venting the gasses that way.



Another point from the pros is they're far less subject to creating the stress cracks that can plague drilled rotors - even the factory ones that were cast with the holes in them then later milled.



Hit up the automotive forums of the more popular modded cars and you'll find that the discussion comes up often - and usually with the same conclusion.



On my previous modded GTP a lot of us had valid reason to improve the brakes - 0 to 60 in 12 seconds on a 3,400 lb car pretty much dictates good brakes in case you "show off" in the wrong place or wanted to make that first turn around after running the 1/4 mile. A lot of people shelled out many hundreds of $$ putting on drilled &/or slotted top brand stuff but those of us that got the best results did so by a simple mod we came up with that allowed us to mount the dual-piston caliper 12" brakes from the GM LS-6 type cars on the front to replace our factory single piston 11" setups. The extra inch in OD made a lot of diffference as did the fact that the pads made for the dual-piston calipers had a slot in the middle of them. With this setup we could go 60-0 in 92 feet -same as a stock Corvette of the same year.



There's also a greater improvement in wet braking with slotted rotors vs drilled.



I'd change the front disk on mine in a heartbeat if I could find a slotted bolt-on replacement as I feel the brakes are definitely inadequate for these bikes. Perhaps some reverse engineering on a lot of replacement disc websites that actually show sizing would be worth trying, much like we're starting to learn a lot more about fork interchangability.
 

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one point you guys missed is that slotted rotors scrape away the glaszed surfaces from the pads and brake dust to keep them fresh for best stopping results. but in doing this they eat pads a little faster then standered disc's. i have a set of rotora slotted brakes and EBC red pads on my sup'd up subie and they are by far better then the stock set up i had before. they grab so much more my anti-lock braking system has a hard time keeping them from locking up under hard braking, which is nuts.
 

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"A lot of people shelled out many hundreds of $$ putting on drilled &/or slotted top brand stuff but those of us that got the best results did so by a simple mod we came up with that allowed us to mount the dual-piston caliper 12" brakes from the GM LS-6 type cars on the front to replace our factory single piston 11" setups. The extra inch in OD made a lot of diffference"



That's comparing apples to oranges. that was not modifying a rotor that's changing the front brake system. That's like me saying my CX500 now stops like a new GSX-R (it does) because I did a simple mod. I changed the calipers and rotors lines and M/C that's a conversion. Not to belabor the point, I have not heard of anyone having their rotor come apart because of stress cracks due to drilling. I would always offer a disclaimer of "be aware of the critical nature of any job and the limits of your skills and resources." Brakes are very important to say the least and there are professionals that will cross-drill your rotors for a fee. Any weight reduction on a rotating mass is immediately felt and adds a perfomance impovement at all speeds whether braking, turning, or accelerating. In a paper released by TAW Vehicle Concepts (wheels) states that each ounce (28.375 grams) at the wheel rim adds 25 pounds of force at 100 MPH. Finally drilled rotors look cool which is half the reason many people do these mods to their bikes.

Cheers, 50gary
 

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Just meant to be an example of a way to improve something, in other words I think it's time we started exploring options that involve bolt-on solutions rather than drilling a bunch of holes in an old piece of steel.



We've found a lot of ways to cross reference stuff over the years, don't see why we can't do the same on brake rotors. For all we know there may be a drilled/slotted one already out there that fits our dimensions perfectly and I'd far rather shell out $35 for one than messing about with the thing myself and yes, I do have a couple of drill presses.



Maybe I'll look a bit myself tonight, I'm kind of temporarily on hold on the fan project.
 

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I just did some calulations on the weight factor of my big 310mm rotors with 66 holes at 7mmm dia. 5mm thick equals a reduction of 7oz. / 200gms for the combined left and right rotors that's a lot. The CX rotors may not be 310 dia they are 275 mm but they are thicker at 7 mm but without actually drilling I'd guess-timate at least 2.5 to 3.5 oz. per rotor.

Cheers, 50gary
 

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That's a lot of holes to put in a rotor with such a limited contact width area. (part of the diameter the pads actually touch)



They say to make sure they're staggered from each other, if you're going to do it I'd mock up some patterns first then center punch every hold really well so there's no chance of the bit slipping.



I'd use real cutting fluid (not just 3-1 oil) and plenty of it. Nothing takes the edge off a drill bit faster than heat. It would be great to have a pan of the stuff underneath and a small pump, true cutting fluid is cheap since it mixes with water.



http://en.wikipedia.org/wiki/Cutting_fluid
 

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If I was going to do this, I would do it on the HAAS minimill at work. CNC would make quick work of the drilling.
 

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There is a guy on e-bay that surface grinds the rotors. He does not use a automotive machine. He also has different patterns/combinations of holes and slots. Very cool. If I can find the post I will edit this posting.



Found it.



http://cgi.ebay.com/...RK%3AMEWAX%3AIT


Interesting! The guy is in my local area! HMMMMMMMM



Joel in the Couve
 

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well as i have been thinking about this i think it would be easier to just replace the rotor with a drilled one that would be the same mm and bolt pattern that way all you have to do is bolt and go
 

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I'd love to find a drilled &/or preferrably slotted rotor that would fit but haven't a clue how we'd go about figuring out what rotors interchange between different bikes.
 

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The question in my mind is I don't intend to race my bike but will from time to time push it harder than normal. I think the improvement in brake pads along with the gas and water evacuation offered by drilled rotors are worth it. I don't think I'll ever push the brakes as hard as racers will repeatedly and that normal street use won't tax the rotor to fail. I've never heard of anyone having a rotor come apart on a street bike after it was drilled.



If the drilled rotor won't give me the performance I need then I will be switching forks to a dual disk dual piston caliper design with a fork brace. I know that will work to stop me quick.



H-H compound EBC pads until then.
 
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